From: Marc Schmitt <mschmitt@inf.ethz.ch>
Subject: Re: nfsd and kswapd
Date: Mon, 07 Jun 2004 10:21:46 +0200
Sender: nfs-admin@lists.sourceforge.net
Message-ID: <1086596506.24334.9.camel@ikarus.inf.ethz.ch>
References: <002201c44c18$23f45e00$0200000a@CARTMAN>
Mime-Version: 1.0
Content-Type: text/plain
Cc: nfs@lists.sourceforge.net
To: Amir Hermelin <amir@montilio.com>
In-Reply-To: <002201c44c18$23f45e00$0200000a@CARTMAN>
Errors-To: nfs-admin@lists.sourceforge.net

Hi Amir,

On Mon, 2004-06-07 at 00:46, Amir Hermelin wrote:
> Hi,
> I'm observing a strange phenomenon running nfsd on 2.4.20 (RH).  I'm using a
> dual-Xeon server with 6GB of memory, and 40 nfsd threads running.  Under
> very heavy load, after a while kswapd starts constantly occupying between
> 60-90% cpu, and every once in a while keventd also wakes up with some 10-
> 30% of its own.  This obviously slows the system and greatly reduces the nfs
> performance.  The strangest thing is, that when I reduce the memory to 512MB
> (with the mem boot option), kswapd seems to be getting a lot less CPU.
> 
> Any explanations on the matter would be greatly appreciated.

Is that a RH 7.3 system? If so, make sure you're running kernel
2.4.20-28 or later, it has the memory management of RH 9 backported and
behaves much better in a setup like yours.

There were many discussions about this on the Dell Linux PowerEdge list,
one thread started here:
http://lists.us.dell.com/pipermail/linux-poweredge/2003-May/024785.html

One workaround is to disable swap, not sure if that's on option for you
though. Depends on what you're running other than file serving.

Greetings,
     Marc


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